Providing an external source of power to a mobile device, such as a personal digital assistant (“PDA”), wireless two-way messaging device, cellular phone, and others, requires design considerations with respect to both the mobile device and the power source. Most mobile devices provide a distinct power interface for receiving power from a power source, for instance to recharge a battery, and a separate data interface for communicating. For example, many mobile devices use USB (Universal Serial Bus) interfaces for communicating and use a separate power interface, such as a barrel connector, for receiving power.